For the sauce you need fermented vegetable liquid; we use the liquid from Peace Love sauerkraut or Life in a Jar vegetables, available at health-food shops and delicatessens. Start this recipe at least five days ahead to ferment the chilli mixture.

Ingredients

2 tsp cumin seeds, dry-roasted

1 tsp whole black peppercorns

6 garlic cloves, finely chopped

¼ cup (loosely packed) oregano

1 tbsp dried oregano

125 ml (½ cup) olive oil

2 tbsp red wine vinegar

1 kg flank steak, trimmed, cut into thin strips

3 white onions, thickly sliced into rounds

4 light-green banana chillies

Fermented green chilli sauce

600 gm long green chillies, halved lengthways

6 garlic cloves, coarsely chopped

2 spring onions, coarsely chopped

60 ml (¼ cup) fermented vegetable liquid

2½ tbsp raw caster sugar

2 tbsp finely grated ginger

150 gm drained canned tomatillos, coarsely chopped

½ cup (loosely packed) coriander, coarsely chopped

2 tbsp olive oil

Method

Main

1

For fermented green chilli sauce, discard seeds from half the chillies, then coarsely chop. Add to food processor with garlic, spring onions, vegetable liquid, 2 tbsp caster sugar, ginger and 1 tbsp fine sea salt flakes, process until finely chopped, then transfer to a sterile 1-litre jar. Tap jar gently on the bench to remove air bubbles, cover with lid, but do not seal and set aside at room temperature to ferment (3-5 days, depending on climate). Stir with a sterile spoon every day, wiping sides of the jar with a clean paper towel. The chilli sauce will be ready when there are small bubbles in the jar and it has a slightly fermented smell. Seal lid and refrigerate for up to a month. Makes about 600ml.

2

Crush cumin seeds, peppercorns and 2 tsp salt with a mortar and pestle. Add garlic, oregano, and dried oregano, pound to a paste, then stir in 80ml olive oil and vinegar. Place flank steak in a large container or bowl, add marinade, toss to coat and refrigerate to marinate (8 hours to overnight).

Preheat a char-grill or barbecue to medium-high. Thread steak onto large skewers and set aside. Brush onions and banana chillies with remaining olive oil and grill, turning occasionally, until charred and tender (8-10 minutes).

5

Char-grill steak, turning occasionally, until charred and cooked to your liking (4-5 minutes for medium-rare). Set aside to rest (5 minutes), then serve with fermented green-chilli sauce and char-grilled onions and banana chillies.